Reciprocating liquid pump with disc check valve for dispensing lotion and the like

ABSTRACT

A manually operated pump comprises a pump housing and a plunger. The pump housing has a pump chamber and an intake port. The plunger extends into the pump chamber. A piston is on the plunger and is reciprocally and axially slidable within the pump chamber between a bottom stroke position and a top stroke position. The fluid pump further includes a priming valve, a check valve, a sealing plug, and a plug seat. The priming valve permits fluid to flow upward through the pump chamber when the piston stroke moves the piston downward from the top stroke position toward the bottom stroke position, and prevents fluid from flowing upward through the pump chamber when the piston stroke moves the piston upward from the bottom stroke position toward the top stroke position. The check valve has a valve seat and a moveable valve member moveable between a closed position in which the moveable valve member moveable between seated and unseated positions. The plug seat is downstream of the check valve and upstream of the priming valve. The sealing plug is configured to seat against the plug seat and seal closed the intake fluid flow path when the piston is in its bottom stroke position to prevent fluid from flowing upward through the intake fluid flow path. The moveable valve member of the check valve and one of the sealing plug and plug seat are of a single unitary piece.

This application is a continuation of U.S. patent application Ser. No.08/646,441, filed May 7, 1996 now U.S. Pat. No. 5,794,821.

BACKGROUND OF THE INVENTION

This invention relates to a manually operated reciprocating fluid pumpfor dispensing lotions and other liquids.

A conventional reciprocating liquid pump for a lotion-type dispensertypically includes a plunger with a dispensing head that is manuallyreciprocated downwardly into a pump housing connected to a liquidcontainer, a spring for biasing the plunger upwardly out of the pumphousing, a priming valve, and a check valve. The priming valve unseats(opens) on the downward movement of the plunger into the pump housing toallow air in the empty pump housing to escape through the plunger anddispensing head, and then seats (closes) on the return stroke of theplunger upwardly out of the pump housing to draw liquid in the containerup into the pump housing. The check valve seats on the downward movementof the plunger to prevent air or any liquid contained in the pumphousing from being forced back into the container, and then unseats onthe upward movement of the plunger to allow the vacuum created in thepump housing by the plunger's upward movement to draw liquid from thecontainer past the check valve into the pump housing.

Often, ball valves are used for both the priming valve and check valvein manually reciprocated liquid pumps. However, ball valves typicallyrequire inwardly directed protrusions or some other type of stop toprevent the ball from traveling too far away from the valve seat. Suchprotrusions and stops are difficult to mold and increase the cost ofmanufacture. Also, when gritty product is the fluid to be dispensed, itoften prevents a ball valve from seating properly against the valveseat, thereby reducing the effectiveness of the dispenser. Anotherdisadvantage of ball valves is that the functioning of ball valves isdependent on gravitational forces which direct the ball of the valvedownwardly to its seated position. If a liquid container having areciprocating pump with ball valves is moved from its uprightorientation, e.g., if it is placed on its side or inverted duringshipment, gravity no longer seats the ball valves and the liquid in thecontainer can pass through and leak from the pump.

SUMMARY OF THE INVENTION

Among the several objects of the present invention may be noted theprovision of an improved liquid dispenser; the provision of such adispenser which avoids the use of ball valves; the provision of such adispenser which effectively dispenses a wide variety of liquid productsincluding gritty products; the provision of such a dispenser having apriming valve and a check valve which are operable regardless of whetherthe dispenser is placed upright, inverted, or on its side; the provisionof such a dispenser configured to prevent leakage when the dispenser isinverted or placed on its side; and the provision of such a dispenserwhich is of relatively simple construction and which is relativelyinexpensive to manufacture.

In general, a manually operated reciprocating fluid pump of the presentinvention comprises a pump housing and a plunger. The pump housing hasan inner surface, an intake port, and a pump chamber defined at least inpart by the inner surface. An intake fluid flow path is defined at leastin part by the pump housing and provides fluid communication between theintake port and the pump chamber. The plunger is configured forextending axially downwardly into the pump chamber. A piston is on theplunger and is slidable within the pump chamber. It is configured forbeing in sealing engagement with the inner surface of the pump housingall around the piston to seal against leakage of fluid between the innersurface of the pump housing and the piston. The piston is reciprocallyand axially slidable within the pump chamber between a bottom strokeposition and a top stroke position. The top stroke position is spacedaxially above the bottom stroke position.

The fluid pump further includes a priming valve, a check valve, asealing plug, and a plug seat. The priming valve is configured to beopen and thereby permit fluid to flow upward through the pump chamberwhen the piston stroke moves the piston downward from the top strokeposition toward the bottom stroke position. It is further configured tobe closed and thereby prevent fluid from flowing upward through the pumpchamber when the piston stroke moves the piston upward from the bottomstroke position toward the top stroke position. The check valve is inthe intake fluid flow path and has a valve seat and a moveable valvemember moveable between a closed position in which the moveable valvemember seats against the valve seat to seal against fluid leakage fromthe pump chamber to the intake port and an open position in which atleast part of the moveable valve member is spaced away from the valveseat to permit fluid to flow from the intake port to the pump chamber.The plug seat is within the intake fluid flow path. The sealing plug isconfigured to seat against the plug seat and seal closed the intakefluid flow path when the piston is in its bottom stroke position toprevent fluid from flowing upward through the intake fluid flow path.The sealing plug is configured to be unseated from the plug seat whenthe piston is positioned above its bottom stroke position. The moveablevalve member of the check valve together with one of the sealing plugand plug seat are of a single unitary piece.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view, in section, of a lotion dispenser ofthe present invention showing a piston of the dispenser in a bottomstroke position;

FIG. 2 is a side elevational view, in section, of the lotion dispenserof FIG. 1 showing the piston in a top stroke position;

FIG. 3 is a side elevational view of a seal member of the lotiondispenser of FIGS. 1 and 2, the seal member having a generally tubularportion defining a plug seat and a flexible disc-shaped flapconstituting a moveable valve member of a check valve;

FIG. 4 is a side elevational view, in section, of the seal member ofFIG. 3;

FIG. 5 is a bottom plan view of the seal member of FIG. 3;

FIG. 6 is a top plan view of the seal member of FIG. 3; and

FIG. 7 is an enlarged fragmented side elevational view, in section, ofthe lotion dispenser of FIG. 1 showing the seal member of FIG. 3 withina pump housing of the lotion dispenser.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, a lotion dispenser of the presentinvention is indicated in its entirety by the reference numeral 20.Although characterized as a lotion dispenser, it is to be understoodthat other liquids may be dispensed via the lotion dispenser 20 withoutdeparting from the scope of this invention. The lotion dispenser 20comprises a pump housing, generally indicated at 22, a plunger,generally indicated at 24, and a lotion dispensing head, generallyindicated at 26.

The pump housing 22 has a tubular, cylindrical configuration 28 with agenerally cylindrical interior surface 30. A ring 32 is formed at thetop of the pump housing 22 and is configured for seating on the top edgeof a liquid bottle (not shown). A threaded collar (or cap) 34 is mountedon the pump housing 22 for rotation about a central axis X of thehousing. The threaded collar 34 receives a threaded neck (not shown) ofthe bottle. A pair of vent openings 36 extend through the pump housing22 just below the ring 32 to vent the bottle interior through thehousing interior. The cylindrical interior surface 30 of the pumphousing 22 defines, in part, a pump chamber 38 for receiving the plunger24.

Referring now to FIGS. 3-7, a monolithic (unitary) one-piece sealmember, generally indicated at 40, is within a lower end of the pumpchamber 38. The pump housing 22 further includes a lower tubular portion41 below the pump chamber 38. The seal member 40 includes a base portion42 sized and configured for being press-fit or otherwise secured in anupper end of the lower tubular portion 41, an upstanding tubularprojection 43 extending upward from the base portion into the pumpchamber 38, a protrusion 44 extending downwardly from the base portion,and a thin, generally disc-shaped flap 46 extending radially outwardlyfrom the protrusion. The base portion has a circular shoulder 110 thatextends radially outwardly from the base portion. The base shoulder hasa bottom surface 112 that engages a ledge 114 of the pump housing thatprojects radially inwardly from the pump housing interior surface 30into the liquid flow path. The base shoulder also has a top surface 116.The spring 90 engages the base shoulder top surface 116 and holds thebase in its press fit axial position relative to the pump housing. Thedisc-shaped flap 46 is engageable with an annular shoulder 47 (FIG. 7)of the lower tubular portion 41 of the pump housing 22. Preferably, theseal member 40 is of a suitable elastomeric material, such as lowdensity polyethylene (LDPE), so that the thin disc-shaped flap 46 isflexible.

The disc-shaped flap 46 and the annular shoulder 47 constitute acheck-valve, generally indicated at 48. In particular, the disc-shapedflap 46 constitutes a moveable check-valve member (also indicated byreference number 46) of the check-valve 48, and the annular shoulder 47constitutes a check-valve seat 47. The annular check-valve seat 47defines an intake port 50 of the pump housing 22 adapted for fluidcommunication with a source of fluid (e.g., liquid in the bottle). Anintake fluid flow path through liquid channels 118 the seal member 40provides fluid communication between the intake port 50 and the pumpchamber 38. The disc-shaped check-valve member 46 is moveable between aclosed (or seated) position and an open (or unseated) position. In theclosed position (shown in solid in FIG. 7), the flexible check valvemember sealingly engages the check-valve seat 47 all around thecheck-valve seat to block fluid communication between the pump chamber38 and the intake port 50. In the open position (shown in phantom inFIG. 7), at least a part of the moveable check-valve member 46resiliently flexes upwardly away from the check-valve seat 47 to therebyprovide a gap between the moveable check-valve member and thecheck-valve seat for fluid communication between the intake port and thepump chamber 38. Because of the shape and flexibility of the check-valvemember 46, the check-valve member desirably moves between its open andclosed positions even when a gritty liquid is being dispensed.

A dip tube 54 is secured to the bottom end of the lower tubular portion41 of the pump housing 22 and is preferably configured for extendingdownwardly to the bottom of the bottle.

The plunger 24 is configured for extending axially downwardly into thepump chamber 38 of the pump housing 22 and has a cylindrical, tubularconfiguration 56 with a cylindrical interior passageway 58 therein. Adownwardly extending protrusion 60 is located generally at a bottomportion of the plunger 24 and under the cylindrical interior passageway58 of the plunger. Preferably, the protrusion 60 is generally circularin transverse cross-section (i.e., as viewed in a cross-section takenalong a plane perpendicular to the axis X) and has a generallyhemispherical lower end. The protrusion 60 includes lateral slits 62therethrough for passage of liquid through the slits and into theinterior passageway 58 of the plunger 24. The lateral slits 62 and theinterior passageway 58 of the plunger 24 constitute a discharge fluidpassageway 64 of the plunger. The lotion dispensing head 26 is securedto the top end of the plunger 24. It includes a discharge port 66 and apassageway 68 through the dispensing head 26 in fluid communication withthe discharge fluid passageway 64 of the plunger 24. Because of this,liquid flowing upwardly through the plunger can flow through and bedispensed from the lotion dispensing head 26 via the discharge port 66.Although the dispenser 20 preferably has a lotion dispensing head, otherheads may be employed without departing from the scope of thisinvention. For example, the lotion dispensing head 26 may be replaced bya spray head specifically designed to dispense liquid from the head in aspray pattern. The spray head would likely be preferred when the pump ofthe invention is employed in dispensing a less viscous fluid from thecontainer.

Preferably, the dispensing head 26 has a locking tab 72 projectinglaterally from one side of the head. The locking tab 72 engages beneathan annular flange 74 (FIG. 1) of a locking ring 76 secured to the upperend of the pump housing 22. The flange 74 of the locking ring 76 has anopening 78 at one position on its circumference that allows the lockingtab 72 to pass therethrough. By rotating the lotion dispensing head 26relative to the threaded cap 34 so that the locking tab 72 is alignedwith the opening 78, the dispensing head and plunger 24 are free toreciprocate through a stroke movement of the plunger relative to thepump housing 22. By depressing the plunger 24 downwardly through thelocking ring 78 and threaded cap 34 so that the locking tab 72 passesthrough the locking ring opening 78, and then by rotating the lotiondispensing head 26 so that the locking tab does not align with theopening, the plunger 24 is locked in its relative position to the pumphousing 22. A sealing ring 80 is also provided between the exterior ofthe plunger 24 and the interior of the locking ring 76 for providing afluid-tight seal between the interior surface 30 of the pump housing 22and the bottle exterior.

A piston 82 is formed on the exterior of the plunger 24 andcircumscribes the downwardly extending protrusion 60. The piston 82 isslidable within the pump chamber 38 and is configured for sealingengagement with the inner surface of the pump housing 22 all around thepiston to seal against leakage of fluid between the inner surface of thepump housing and the piston. The piston 82 is reciprocally slidablewithin the pump chamber 38 along the axis X between a bottom strokeposition (FIG. 1) and a top stroke position (FIG. 2). The piston 82 andpump chamber 38 define a variable volume fluid receiving cavity 84. Thefluid receiving cavity 84 has a first volume V₁ when the piston 82 is inits top stroke position (FIG. 2) and has a second volume V₂ smaller thanthe first volume V₁ when the piston is in its bottom stroke position(FIG. 1). The discharge fluid passageway 64 of the plunger 24 anddispensing head 26 constitute a discharge fluid flow path for providingfluid communication between the fluid receiving cavity 84 and thedischarge port. The plunger 24 has an annular shoulder 88 formed on itsexterior surface that engages against the underside of the sealing ring80 to limit upward movement of the plunger 24. A coil spring 90 ispositioned between the bottom of the plunger 24 and the bottom of thepump chamber 38 of the pump housing 22. The spring 90 extends around theupstanding tubular projection 43 of the seal member 40 and engages thebase portion 42. The spring 90 biases the plunger 24 upwardly to its topstroke position relative to the pump housing and further maintains theposition of the seal member 40 relative to the pump housing.

A priming valve 92 is mounted on the plunger 24 adjacent the protrusion60 of the plunger and radially inwardly of the piston 82 for movementwith the plunger. The protrusion 60 is shaped and configured for actingas a valve seat for the priming valve 92. The priming valve 92 has aresilient tubular portion 94 engageable with the protrusion 60, and anannular sealing flange 96 just below and circumscribing the tubularportion. The sealing flange 96 is configured for sealing against anannular shoulder 98 defined by the inner surface of the plunger 24 allaround the sealing flange to prevent leakage of fluid therebetween.Because the priming valve 92 moves with the plunger 24, the sealingflange 96 remains sealed to the annular shoulder 98 of the plungerregardless of whether the priming valve is open or closed. Preferably,the upper end of the coil spring 90 presses upwardly against the annularsealing flange 96 to bias it in sealing engagement with the annularshoulder 98. The priming valve 92 further includes a sealing plug 100(described in greater detail below) and lateral openings 102 through thesealing plug providing a fluid passage through the priming valve. Thepriming valve 92 is moveable between a closed position and an openposition. In the closed position, the resilient tubular portionsealingly engages the protrusion 60 all around the tubular portion toblock fluid communication between the discharge fluid passageway 64 ofthe plunger 24 and the fluid receiving cavity 84. In the open position,at least a part of the tubular portion 94 flexes generally radiallyoutwardly away from the protrusion 60 to thereby provide a gap betweenthe tubular portion and protrusion for fluid communication between thefluid receiving cavity 84 and the discharge fluid passageway 64 of theplunger 24.

The sealing plug 100 and priming valve 92 are of a single unitary pieceand preferably formed of an elastomeric material. The sealing plug 100is configured to seat against and seal closed the upstanding tubularprojection 43 of the seal member 40 when the piston 82 is in its bottomstroke position to prevent fluid from flowing upward through the pumpchamber 38. Thus, the upper end of the tubular projection 43 constitutesa plug seat. When the piston 82 is positioned above its bottom strokeposition, the sealing plug 100 is spaced above the upstanding tubularprojection 43 of the pump housing 22 and is therefore unseatedtherefrom.

The liquid pumping and dispensing operation of the lotion dispenser 20is similar to that of conventional reciprocating pumps. Manuallydepressing the lotion dispensing head 26 downwardly causes the plunger24 and piston 82 to move downwardly to the bottom stroke position. Thisdownward movement causes the resilient tubular portion 94 of the primingvalve 92 to flex radially outwardly to open the priming valve andthereby permit fluid, whether air when initially priming the pump or thecontainer liquid after the pump has been primed, to pass from the pumpchamber 38 through the priming valve through the lateral slits 62 of theprotrusion 60 into the discharge fluid passageway 64 of the plunger 24and out the discharge port 66 of the lotion dispensing head. Releasingthe manual force on the lotion dispensing head 26 allows the coil spring90 to push the plunger 24 and piston 82 upwardly to the top strokeposition. This upward movement creates a vacuum in the fluid receivingcavity 84 which unseats the moveable check-valve member 46 and drawsliquid up the dip tube 54 through the seal member 40 and into the fluidreceiving cavity 84. This vacuum also forces the resilient tubularportion 94 of the priming valve 92 radially inwardly to close thepriming valve. By continued reciprocating movement of the plunger 24relative to the pump housing 22, the liquid is continued to be drawnfrom the container and dispensed through the dispensing head 26.

When the plunger 24 and piston 82 are in their bottom stroke positionsand when the dispensing head 26 is locked to the collar 34 as shown inFIG. 1, the plug 100 seats against the upstanding tubular projection 43of the seal member 40 to block flow of fluid through the dispenser 20.In this position, liquid will not leak from the dispenser 20 even if thedispenser is tilted or inverted. Because the seal member 40 includesboth the plug seat and the moveable check valve member 46, the othercomponents of the dispenser 20 are of simpler shapes which reduce thecost of manufacture of these other components.

Although the seal member 40 preferably includes both a plug seat and amoveable check valve member, it is to be understood that otherconstructions are possible without departing from the scope of thisinvention: For example, instead of having the plug seat 43 on the sealmember 40 which receives a sealing plug 100 of the priming valve 92, theseal member could have a sealing plug which engages a plug seat formedwith the priming valve. With such a modified dispenser, it is to beunderstood that the sealing plug would include lateral openings similarto the lateral openings 102 associated with sealing plug 100.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above construction withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense. The invention therefore shall be limited solely by the scope ofthe claims set forth below.

What is claimed is:
 1. A manually operated reciprocating fluid pumpcomprising:a pump housing having an interior surface, an intake port,and a pump chamber defined at least in part by the interior surface,said pump chamber extending axially within the pump housing; an intakefluid flow path defined at least in part by the pump housing, saidintake fluid flow path providing fluid communication between the intakeport and the pump chamber; a plunger configured for extending axiallydownwardly into the pump chamber; a piston on the plunger and in thepump chamber, the piston being configured for sealing engagement withthe interior surface of the pump housing to seal against leakage offluid between the interior surface of the pump housing and the piston,the piston being reciprocally and axially slidable within the pumpchamber between a bottom stroke position and a top stroke position, thetop stroke position being spaced axially above the bottom strokeposition; a priming valve configured to be open and thereby permit fluidto flow upward through the pump chamber when the piston stroke moves thepiston downward from the top stroke position toward the bottom strokeposition, the priming valve further being configured to be closed andthereby prevent fluid from flowing upward through the pump chamber whenthe piston stroke moves the piston upward from the bottom strokeposition toward the top stroke position; a check valve in the intakefluid flow path having a valve seat and a moveable valve member moveablebetween a closed position in which the moveable valve member seatsagainst the valve seat to seal against fluid leakage from the pumpchamber to the intake port and an open position in which at least partof the moveable valve member is spaced away from the valve seat topermit fluid to flow from the intake Port to the pump chamber, the valveseat being an annular shoulder and the valve member being a flexibledisc; the flexible disc has a center portion and a circular peripheraledge around the center portion, and in the open position of the checkvalve the peripheral edge is spaced away from the valve seat.
 2. Thepump of claim 1, wherein:the peripheral edge of the disc rests on theannular shoulder in the closed position of the check valve.
 3. The pumpof claim 1, wherein:the check valve has a center protrusion that issecured stationary in the intake fluid flow path and the centerprotrusion supports the flexible disc at the center portion of the disc.4. The pump of claim 3, wherein:the protrusion is secured stationary inthe intake port.
 5. The pump of claim 3, wherein:the protrusion is pressfit into the intake port.
 6. The pump of claim 3, wherein:the peripheraledge of the disc is free to move relative to the protrusion.
 7. The pumpof claim 3, wherein:a plurality of liquid channels are arranged aroundthe protrusion and define a part of the intake fluid flow path providingfluid communication between the intake port and the pump chamber.
 8. Thepump of claim 7, wherein:the check valve includes a base that is pressfit into the intake port and the protrusion and the disc are supportedby the base.
 9. The pump of claim 8, wherein:the plurality of liquidchannels bypass the base.
 10. The pump of claim 8, wherein:the pumphousing has a ledge surface that projects inwardly from the interiorsurface of the pump housing, and the base has an annular shoulder thathas a bottom surface that engages the ledge surface of the pump housingto axially locate the base relative to the pump housing.
 11. The pump ofclaim 8, wherein:a spring is contained in the pump housing and biasesthe piston toward the top stroke position, and the base has a shoulderthat has a top surface and the spring engages the top surface to axiallylocate the base relative to the pump housing.
 12. A manually operatedreciprocating fluid pump comprising:a pump housing having a pump chamberand an intake port axially below the pump chamber; an intake fluid flowpath providing fluid communication between the intake port and the pumpchamber; a plunger extending axially downward into the pump chamber, theplunger having a piston thereon, the piston being reciprocally andaxially slidable in the pump chamber between a bottom stroke positionand a top stroke position; a check valve in the intake fluid flow pathhaving a valve seat and a moveable valve member moveable between aclosed position in which the valve member seats against the valve seatto seal against fluid leakage from the pump chamber to the intake portand an open position in which at least part of the valve member isspaced away from the valve seat to permit fluid to flow from the intakeport to the pump chamber, the valve seat is an annular shoulder and thevalve member is a flexible disc supported on a base that is press fitinto the intake port; and, the flexible disc has a center portion thatis connected to the base and is held stationary in the intake port bythe base and a circular peripheral edge around the center portion, inthe open position of the check valve the peripheral edge is spaced awayfrom the annular shoulder and in the closed position of the check valvethe peripheral edge rests on the annular shoulder.
 13. The pump of claim12, wherein:a plurality of liquid channels bypass the base and providefluid communication between the intake port and the pump chamber. 14.The pump of claim 12 wherein:the check valve has a center protrusionthat is centered axially relative to the pump chamber, the protrusion isconnected to the center portion of the disc and connects the disc to thebase.
 15. The pump of claim 14, wherein:a plurality of liquid channelsare arranged around the center protrusion.
 16. The pump of claim 14,wherein:the disc, the protrusion and the base are a single componentpart that is assembled into the pump housing.
 17. A manually operatedreciprocating fluid pump comprising:a pump housing having a pump chamberand an intake port axially below the pump chamber; an intake fluid flowpath providing fluid communication between the intake port and the pumpchamber; a plunger extending axially downward into the pump chamber, theplunger having a piston thereon, the piston being reciprocally andaxially slidable in the pump chamber between a bottom stroke positionand a top stroke position; a check valve in the intake fluid flow pathhaving a valve seat and a moveable valve member moveable between aclosed position in which the valve member seats against the valve seatto seal against fluid leakage from the pump chamber to the intake portand an open position in which at least part of the valve member isspaced away from the valve seat to permit fluid to flow from the intakeport to the pump chamber, the valve seat is an annular shoulder and thevalve member is a flexible disc supported on a base that is press fitinto the intake port; and, the pump housing has a ledge surface thatprojects inwardly into the fluid flow path and the base has an annularshoulder with a bottom surface that engages the ledge surface of thepump housing to axially locate the base relative to the pump housing.18. A manually operated reciprocating fluid pump comprising:a pumphousing having a pump chamber and an intake port axially below the pumpchamber; an intake fluid flow path providing fluid communication betweenthe intake port and the pump chamber; a plunger extending axiallydownward into the pump chamber, the plunger having a piston thereon, thepiston being reciprocally and axially slidable in the pump chamberbetween a bottom stroke position and a top stroke position; a checkvalve in the intake fluid flow path having a valve seat and a moveablevalve member moveable between a closed position in which the valvemember seats against the valve seat to seal against fluid leakage fromthe pump chamber to the intake port and an open position in which atleast part of the valve member is spaced away from the valve seat topermit fluid to flow from the intake port to the pump chamber, the valveseat is an annular shoulder and the valve member is a flexible discsupported on a base that is press fit into the intake port; and, aspring is contained in the pump housing and biases the piston toward thetop stroke position, and the base has a shoulder that has a top surfaceand the spring engages the top surface to axially locate the baserelative to the pump housing.